Convert bmp to rfg Online: bmp2rfg
You can use Tom's Editor to easily convert images from
Microsoft Windows bitmap .BMP to LEGO Mindstorms EV3 Robot Graphics File .RFG.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Format created by Microsoft for their Windows and OS/2 operating systems. Images can be compressed or not.
LEGO Mindstorms EV3 Robot Graphics File is an image format with extension RFG.